Surgical air drill

ABSTRACT

An improved surgical air drill having a novel, detachable hand piece assembly with an integral cutting burr. The hand piece is interchangeable with others having different burrs or cutting heads and may be removed and replaced while the drill motor is operating at full speed. The particular configuration of the coupling between the motor and the hand piece permits such interchanging to be accomplished with ease while assuring that the burr remains axially true.

nite States Patent 1191 agen Sept. 17, 1974 [5 SURGICAL AIR DRILL2,885,232 5/1959 Eberly 64/9 R W51 Inventor: Clarence Hagen, Long Beach,2:135:33 111323 522;:...........:::::::::::: 1333.1?3532 3,667,125 61972 Seigneurin 32/26 [73] Assignee: Edward Weck & Company, Inc.,

Long Island, NY. Primary ExaminerRichard A Gaudet AssistantExaminerHenry .1. Recla [22] Filed Sept 1972 Attorney, Agent, orFirm-Weingarten, Maxham & [2]] Appl. No.: 286,465 Schurgin [52] US. Cl128/305, 408/141, 32/26 1 1 ABSTRACT [51] 111 CI A6lb 17/00 An improvedsurgical air il having a novel, detach [58] meld of Search 128/305 304131 able hand piece assembly with an integral cutting burr. 128/333303-14; 32/26 The hand piece is interchangeable with others having 56,59, DIG. 1; 408/141, 702, 142, 713; 6 different burrs or cutting headsand may be removed 1 l C; 287/104 2092 20-92 K; and replaced while thedrill motor is operating at full 285/4, 347 speed. The particularconfiguration of the coupling between the motor and the hand piecepermits such [56] References cued interchanging to be accomplished withease while as- UNITED STATES PATENTS suring that the burr remainsaxially true.

462,530 11/1891 Booth 32/26 2,666,259 1/1954 Thaii-Jensen .1 32/26 1 3Drawmg F'gures PAIENIEBSEPITIQII v ma asgase SHEET 2 BF 2 SURGICAL AIRDRILL FIELD OF THE INVENTION This invention relates in general to toolsoperated by rotary air driven motors and more particularly concerns anovel surgical air drill having interchangeable hand piece assemblieswhich include integral burrs, bearings and couplings.

DISCUSSION OF THE PRIOR ART Tools of many types employing air drivenrotary motors are currently available. They are widely used for dentistsdrills and have been used to some extent in the field of surgery,primarily for bone cutting and shaping.

Surgical drills normally use a larger and more powerful motor togetherwith a larger cutting tool or burr than is normal with dental drills.Furthermore, due to the locations which must be reached by the operatingcutter head of the surgical drill it is often necessary that the cuttinghead be spaced a significant distance from the handle which normallycontains the air motor.

Burrs of many different shapes and sizes are likely to be needed, evenduring a single operation and it is thus necessary to provide for readyinterchangeability of the cutting tools. It is also necessary tomaintainthe burr and its shaft absolutely axially true so that the cutting headremains centered without any tendency to deviate during operation inorder to provide the precision required for delicate surgicalprocedures.

Many of the prior art devices have provided an interchangeable cuttingtool which has a shank for removable engagement by some type of chuckcoupled to the motor. Other such instruments have an interchangeableoutboard support where extra length is necessary. In such a device, anelongated tool shank is supported near its outer end by a bearing in theoutboard support and the inner end is supported in the normal manner bya chuck coupled to the air motor. It may be appreciated that most knowntypes of chucks are somewhat flexible and often will permit the burr torotate slightly offcenter, particularly when a sideward force isapplied, as when the burr is in actual surgical use. Furthermore, withan elongated cutting tool of the type which must employ an outboardsupport, it is not unlikely that the shank of the cutting tool couldbecome longitudinally warped to some small degree, thereby causing theburr to generate a small circle, somewhat larger than its own diameter,as it rotates. This, of course, would normally be unacceptable forsurgical or any other precision use.

It is a primary object of this invention to provide an interchangeablehand piece assembly which not only supports its integrally constructedcutting head in truly centered fashion, but may be interchanged evenwhile the air motor is operating at full speed.

SUMMARY OF THE INVENTION This invention generally concerns an improvedsurgical instrument powered by an air motor and having aninterchangeable hand piece and cutting head assembly. A splined shaft,which is coupled to and rotates with the air motor, has an interiorsplined sleeve secured to its forward end. The hand piece also includesa splined shaft configured to mate with the interior splines of thesleeve. The end of the sleeve and the splined end of the hand pieceshaft are configured so as to mate the respective splined elementseasily andpositively, even while the motor is rotating. The cutting toolwhich comprises a burr and a shank is secured to the hand piece shaft ina semi-permanent manner such as by brazing and at least two sets ofbearings are provided in the assembly to insure that the burr remainstruly centered at all times. While the hand piece may have differentlengths, the shank of the burr is short to avoid the possibility oflateral deformation.

An advantage of this device is that even though the burr is operating atfull speed, the outboard assembly may be removed and another oneinserted in its place within a very few seconds without the need ofstopping the air motor. This enables the surgeon to maintain a preferredspeed setting for the air motor and at the same time change to differentburrs as necessary.

BRIEF DESCRIPTION OF THE DRAWING The objects, features and advantages ofthis invention will become more clearly evident from the followingdetailed description when taken in conjunction with the accompanyingdrawing in which:

FIG. 1 is a perspective view of a fully assembled surgical instrumentconstructed in accordance with this invention;

FIG. 2 is an enlarged broken away exploded perspective of the couplingused in the instrument of FIG. 1; and

FIG. 3 is a sectional view of the hand piece and the forward end of thehousing constructed in accordance with this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference now to thedrawing there is shown in FIG. 1 a surgical instrument 1] having a mainhousing 12 enclosing a conventional air motor (not shown) powered by airsupplied through tube 13. Hand piece 14 with its integrally constructedburr 16 is shown attached to the forward end of the main housing 12. Byopening appropriate valves (not shown) the air supplied through tube 13causes the motor within housing 12 to rotate, the speed normally beingvariably controllable. A shaft within hand piece assembly 14 is coupledbetween the motor and shank 15 for rotation of burr 16 as necessary foruse by the operator.

The operative coupling between the air motor and the hand piece is shownin detail in FIG. 2. Within housing 12 is shaft 17 which is directlycoupled to the air motor. The forward end of shaft 17 is formed withsplines 21. Sleeve 22 having an interior splined surface 23 configuredto mate with splines 21 is secured to the end of shaft 17 byconventional means such as pin or screw 24. This sleeve rotates withshaft 17 and is firmly fixed thereto. The forward end of sleeve 22 isformed with surfaces or lands 25 separated by arcuate cutouts 26. Thepurpose of this configuration will become apparent from the detaileddescription hereinbelow of the hand piece shaft.

The rearward end of shaft 27 in hand piece 14 is also formed with asplined outer surface 31, similar to that of shaft 17. These splines areconfigured to mate with the splined configuration of sleeve 22. Therearward end of shaft 27 is formed with radially arranged wedgeshapedridges 32 separated by radial grooves 33. If sleeve 22 and shaft 27 arealigned properly when they are brought together, the outwardlyprojecting splines 34 on shaft 27 will mate with the outwardlyprojecting grooves 35 in the inner surface of sleeve 22. However, it isnot possible to always have the shafts in such perfect couplingalignment and it is manifestly impossible if shaft 17 is rotating. Toaccommodate this fact the particular end configurations of shaft 27 andsleeve 22 have been devised. If outwardly projecting splines 34 arealigned with inwardly projecting splines 36 in sleeve 22, ridges 32 willabut surfaces 25 on the forward end of the sleeve. If shaft 17 isrotating, ridges 32 will very quickly drop off the adjacent edge ofsurface 25 in the vicinity of arcuate cutouts 26. However, when thisoccurs splines 34 are in alignment with grooves 35 and shaft 27 may thenenter and become rotatably coupled with sleeve 22 and shaft 17. It willbe observed that with the tapered shape of ridges 32 on the end of shaft27, a force urging the hand piece and main housing together will causethese ridges to immediately drop between surfaces 25 when they are inalignment with grooves 35. The particular configuration of the rearwardend of hand piece 14 and the forward end of housing 12 facilitates thiscoupling as will become apparent from the further descriptionhereinbelow.

The hand piece assembly 14 is shown in detail in FIG. 3. Housing 41 isformed with internal threads 42 at its rearward end for coupling withcorrespondingly threaded connector 43. Sleeve 44 is secured within theforward end of housing 41 and in turn retains forward cone 45. Theseelements may be secured together by any appropriate means. Anti-frictionbearing 46 is mounted within the forward end of sleeve 44 adjacent cone45. A rearward facing shoulder 47 provides a seat for the forward end ofthe beaing while an internal taper 51 is provided within sleeve 44 tomaintain the bearing at its proper location. It should be noted that thebearing could be maintained in its position by means of retaining ringsat either end thereof if desired rather than using the particularstructure shown.

Shaft 27, having rearward splined end 31 and forward end 52 of reduceddiameter, is rotatably mounted within hand piece 14. The forward end ofthe shaft terminates adjacent the forward end of the hand piece and hasa bore 53 for receiving shank of the cutting tool. This particularconfiguration permits shank 15 to be relatively short compared with thetotal length of the hand piece and cutting tool and therefore lesslikely to become axially misaligned than would a cutting tool having alonger shaft. The tool shank is secured within end 52 of the hand pieceshaft by any suitable means such as brazing or sweating and is centeredand trued when so assembled. The rearward end of shaft 27 is centered bymeans of anti-friction bearing 54 which is retained in place on theshaft by retaining rings 55 and 56. The shaft and bearing are preventedfrom moving rearwardly beyond their normal position as shown by means ofshoulder 57 in connector 43. Rearward facing shoulder 61 within housing41 and located forward of threads 42 provides a seat for springretaining ring 62. Compression spring 63 is provided between ring 62 andbearing 54 and thereby biases shaft 27 rearwardly.

The forward end of air motor housing 12 is provided with tapered entry64 and the rearward end of connector 43 is formed with bevel 65 tofacilitate entry of the connector into the main housing. When theconnector is fully inserted, locking ring 66 engages bevel 67 within themain housing and removably retains the hand piece in place. The innerdiameter of the forward end of housing 12 is slightly larger than theouter diameter of connector 43 to permit free entry and rotation of theconnector. Bevel 68 is provided on connector 43 to seat on tapered entry64. Through the action of locking ring 66, connector 43 is thus seatedtightly against housing 12 to assure that the cutting head maintains itsaxial alignment while permitting the hand piece to swivel freely. Thisswivelling feature is important because the surgeon must manipulate theinstrument at various angles during an operation. By permitting suchrelative rotation, he does not have to be concerned with the angle anddirection at which the hose connects to the instrument because it willalways tend toward one orientation from the work area. Another advantageof this feature is that no rotational alignment is necessary when thehand piece and main housing are assembled.

As previously described, splined end 31 of the hand piece shaft enterssleeve 22 so that the main shaft 17 and the hand piece shaft 27 arecaused to rotate together. Spring 63 is provided to facilitateengagement of the two shafts when the motor is rotating. It will beappreciated that with sleeve 22 rotating very rapidly and shaft 27 notrotating, a perfect match is not likely immediately upon insertion ofthe hand piece into the main housing. In this manner, when ridges 32 ofthe rearward end of shaft 27 make initial engagement with the rotatingsleeve, it is likely that the hand piece shaft will lag slightly therearward motion of the hand piece housing, thereby compressing spring63. However, under the continuous biasing effect of the spring, shaft 27is urged rearwardly and will very quickly mate properly with sleeve 22.It is of course possible to secure the sleeve to the hand piece shaftand reverse the coupling configuration if desired.

It will now be appreciated how this instrument provides a much moreconvenient means for exchanging cutting burrs during surgery. Becausethe burrs have short shafts and are mounted to the hand piece as anintegral part thereof they remain centered indefinitely. This structureeliminates the need for a flexible chuck which could permit the burr tostray from its true axis of rotation. Furthermore, the ability to removea hand piece and insert another within seconds while the motor isoperating at the desired speed is a significant advantage duringsurgery. The high speed connection is further facilitated by the factthat the air motor has a very low rotational inertia thereby permittingits speed to momentarily change upon contacting the hand piece shaft andfacilitating the desired coupling. It is also'possible to replace a wornburr in a hand piece. Since this would be a factory type service,centering would be accomplished anew at that time, so that the useralways has a trued integral hand piece and burr.

In light of the above description it is likely that changes andimprovements will occur to those skilled in the art which are within thescope of this invention.

What is claimed is:

l. A rotary surgical instrument comprising:

a main housing having an air motor mounted therewithin;

means for supplying air under pressure to said motor to cause controlledrotation thereof;

a forwardly extending shaft coupled to said air motor for rotationtherewith;

a hand piece removably coupled to said main housing, said hand piececomprising; a housing; a shaft rotatably mounted within said hand piecehousing; and a cutting tool having a shaft secured to the forward end ofsaid hand piece shaft for rotation therewith; and means for removablycoupling said hand piece shaft to said air motor shaft for rotationtogether of said shafts; said coupling means comprising a sleeve securedto the forward end of said air motor shaft for receiving the rearwardend of said hand piece shaft, the forward end of said air motor shaftand the rearsplines.

1. A rotary surgical instrument comprising: a main housing having an airmotor mounted therewithin; means for supplying air under pressure tosaid motor to cause controlled rotation thereof; a forwardly extendingshaft coupled to said air motor for rotation therewith; a hand pieceremovably coupled to said main housing, said hand piece comprising; ahousing; a shaft rotatably mounted within said hand piece housing; and acutting tool having a shaft secured to the forward end of said handpiece shaft for rotation therewith; and means for removably couplingsaid hand piece shaft to said air motor shaft for rotation together ofsaid shafts; said coupling means comprising a sleeve secured to theforward end of said air motor shaft for receiving the rearward end ofsaid hand piece shaft, the forward end of said air motor shaft and therearward end of said hand piece shaft having similarly splined externalsurfaces, the internal surface of said sleeve having mating splines; theforward end of said sleeve being formed with lands at the ends of theinwardly projecting ridges of said splined surface and depressionsbetween said lands at the ends of the grooves between said ridges; therearward end of said hand piece shaft being formed with radial ridges atthe ends of the outwardly projecting splines and depressions betweensaid ridges at the ends of the grooves between said splines.